It is our impression that Laser angioplasty as a catheter-based technique for the treatment for coronary antherosclerosis will require the accurate identification of target lesions using ultrathin angioscopes. Therefore, to complement our work with laser tissue interactions we have studied commercial fibrotic endoscopes to study the vascular anatomy in 40 anesthetized animals and in 10 human cadaver preparations. Technical modifications were necessary to insure high resolution images and we found that arterial anatomy could be viewed in greater than 95% of vessels greater than 2mm in diameter. We also have attemped to define the design specificastions required for the development of a multifunctional catheter system incorporating angioscopy and a fibrotic waveguide to provide the requisite energy densities of ultraviolet light which would result in effective and safe tissue ablation.